Parody isn't even remotely close to being a case for libel, otherwise The Onion would long since have drowned in ruinous lawsuits. Impersonation requires far more than having a similar or the same username as a known figure and saying obviously stupid shit in their name. Twitter can kick whomever they please out of their platform of course but that doesn't mean parody is now a criminal act.
Myself I'm mostly amused that previous champions of free speech (not talking about you in particular) are now busy explaining to whoever will hear it why it's totally OK for Twitter to be if anything more restrictive of free speech than it was before. And I have an impression that the actual why of it strongly correlates with the fact that it's people they don't like who are getting banned this time.